This invention relates in a first aspect to an electric rotary power tool apparatus holdable by hand during operation; in a second aspect to a kit comprising the novel apparatus, and in a third aspect to novel switch means therefor.
The power tool apparatus according to the first invention aspect consists essentially of
(A) a first building block comprising PA0 (B) a second, rearward building block comprising PA0 (C) a third, inset building block adapted for being practically completely inserted therein by way of the open front end of the said forward shell chamber, and comprising, besides the initially described shaft-bearing means, PA0 (2.3) a rotor mounted inside the motor housing on the driving rotor shaft means for rotating the latter; PA0 (2.4) stator means adapted for generating an electric field for cooperation with said rotor; and PA0 (2.5) commutator means comprising
(1) an apparatus casing consisting essentially of an elongated assembly having a longitudinal axis and comprising PA1 (2) a motor comprising, in turn, PA1 (3) insertable bearing-wall means adapted for being mounted transversely in rigid, detachable connection, in the said open front end of the enveloping shell, and having a central axial throughhole; these insertable bearing-wall means comprise PA1 (3.2) intermediary power-transmitting insert means comprising PA1 (3.3) centering socket means adapted for protruding forward out of the enveloping shell and being located spaced outwardly from said throughhole; and PA1 (3.4) tool fastener-engaging means adapted to be located outside the shell and spaced outwardly of the axial throughhole. These may, for instance, be boltholes. PA1 (2.5.a.) a commutator consisting essentially of collector segments and being mounted on the driving rotor shaft means between the rotor and the said rearward motor housing end wall; PA1 (2.5b.) first and second brush means mounted in the motor housing and biassed toward the collector segments for electrically conductive contact therewith to deliver, preferably direct, electric current to the rotor; PA1 (2.5.c.) first and second fixed contactor means being electrically conductively connected with the first and second brush means, respectively, and being mounted stationary in the rearward building block and having terminal portions located outside the rearward motor housing end wall; the fixed contactor terminal portions bearing contactable surface regions located generally in a substantially planar contact zone; and PA1 (2.5.d.) electrically conductive lead means adapted for connecting the first and second brush means, respectively with the first and second fixed contactor means, substantially free from electrical power losses. This last-mentioned advantageous feature is achieved by providing lead means of a sufficiently large cross sectional area, and by avoiding at the junctions between the lead means and other conductive elements all soldered joints, using instead clamping-in connections ensuring metal-on-metal pressure contact. PA1 (IV.1) nut-loosening and tightening socket means; PA1 (IV.2) screw driver means; PA1 (IV.3) a drilling tool; PA1 (IV.4) a blade saw tool; PA1 (IV.5) an angle tool comprising at least one of sander and cutter means;
(1.1) an enveloping shell extending generally in the direction of the said longitudinal axis, and having an open front end and an open rear end; and being of one piece; PA2 (1.2) a first transverse wall extending across the interior of the shell in a region thereof intermediate the said front end and the said rear end axially spaced from both these ends so as to divide the shell interior into a forward chamber and a rearward chamber; the first transverse wall has a throughhole therein and is integral with the said shell; PA2 (1.3) a second transverse wall across the open rear end of the shell and being detachably mounted therein; the second transverse wall has an opening therein; and PA2 (1.4) a speed-reducing unit which is mounted on the second transverse wall on the side thereof facing toward the first transverse wall, and comprises a driven power-transmitting shaft having a driven shaft front end adapted for fitting into the said throughhole and protruding therefrom into the forward chamber of the shell; PA2 (2.1) a motor housing having a central longitudinal axis substantially parallel with the elongated assembly axis, and comprising a surrounding hull, a forward hull end, a rearward hull end wall, and being adapted for having the front end thereof rigidly connected with the second transverse wall on the outside of the latter; PA2 (2.2) driving motor shaft means extending through the interior of the motor housing and being rotatably supported in the opening of the second transverse wall; the driving rotor shaft means have a forward shaft end extend into the rearward shell chamber and are adapted for drivingly engaging the said speed-reducing unit therein; and PA2 (3.1) shaft-bearing means in the axial throughhole in which a driven power-transmitting shaft of the power tool apparatus can be supported. PA2 (3.2.a) insert shaft means having a forward and a rearward shaft end, of which the rearward shaft end is adapted for driving engagement with the driven shaft front end protruding into the forward shell chamber; the insert shaft means are supported for rotation in the shaft-bearing means in a region of the insert shaft means near the forward shaft end thereof; and PA2 (3.2.b) a connecting piece on the forward shaft end and forward of the shaft bearing means;
An apparatus of the type described hereinbefore has been disclosed by V. Raso and A. C. Eisenhart in their U.S. Pat. No. 3,434,366 granted Mar. 25, 1969.
However, this known apparatus is not intended to be held by hand, especially during operation, but is to be mounted stationary on a solid base 5 on supporting feet 156 (FIG. 1 of U.S. Pat. No. 3,434,366).
If it were adapted to be used by hand it could be used for short tools such as sockets for tightening and loosening nuts or for screwdrivers. However, no heavy duty work could be done with such a power tool, when of reduced size to render it holdable by hand, as the apparatus lacks power-enhancing means such as an impact clutch or the like and could not support the same inside the forward housing of the frame or enveloping sleeve which is only intended to house a gear reduction unit distributed over both the forward and the rearward chamber which are formed in the frame of the Raso et al reduction unit.
A known electrical switch adapted to be mounted on the end part of an electric motor next adjacent the commutator thereof has been described in U.S. Pat. No. 3,681,550 issued on Aug. 1st, 1972 to Perry and Brockelsby. In this known electrical switch, contractor pins 66 extend from a rearward outer plate 62 corresponding to a cap member end wall, infra, in a switch structure through an intermediary cap member 54 into a pivotable brush mounting plate 40 in which there are housed four brushes 47 which are urged with their contactable forward end faces against an insulating wafer 26 having four openings 32 to 35 therein. As the brushes come to register with these openings owing to rotation of the brush mounting plate relative to the wafer, the brushes will penetrate through the openings and come into contact with a conically-shaped surface composed of commutator segments. Flexible wire connections are provided within the brush mounting plate and connect the brushes with the ends of the connector pins lodged in the brush mounting plate.
This known switch is thus of rather complicated structure and suffers from a considerable number of points where the various elements are subject to relatively rapid wear.
In the prior power-tool apparatus known to me, an exchange of impact means or the like present in a forward chamber of the apparatus casing is only provided for by making the forward part of the apparatus casing detachable from the rearward part thereof housing the speed-reducing unit. After the forward apparatus part has been detached, the impact clutch or the like power-transmitting means housed therein can be withdrawn from the forward chamber only by way of the rearward end of the forward part, or, depending on the structure of each casing, part or all of the speed-reducing unit must be removed, before another type of power-transmitting unit can be inserted in that forward chamber.
This is the case in the power tool apparatus described in my U.S. Pat. No. 4,505,170 dated Mar. 19, 1985; in U.S. Pat. No. 4,368,784 to Wunsch et al, granted on Jan. 18, 1983; in German Offenlegungsschrift DE 30 07 630, applied for by Rodac Pneumatic Tools, Carson, Calif., and published on Mar. 12, 1981 (U.S. application Ser. No. 70149 filed on Aug. 27, 1979); in German Offenlegungsschrift DE 30 15 423, applied for by Robert Bosch GmbH, Stuttgart, Germany, and published on Oct. 29, 1981; and in Swiss Pat. No. 553,625 granted to Atlas Copco Aktiebolaget, Nacka, Sweden and published on Sept. 13, 1974.